chore: clean up content phase organization

apps/docs/content/(01-linear-structures)/sliding-window/567-permutation-in-string.mdx

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+---
+title: '567. Permutation in String'
+description: Given two strings s1 and s2, return true if s2 contains a permutation of s1, or false otherwise
+sidebar:
+  label: 'Permutation in String'
+  badge: 'Medium'
+---
+
+<Badge variant="accent">Hash Table</Badge>
+
+### Example 1:
+- Input: `s1 = "ab", s2 = "eidbaooo"`
+- Output: `true`
+- Explanation: `s2` contains one permutation of `s1` ("ba").
+
+### Example 2:
+- Input: `s1 = "ab", s2 = "eidboaoo"`
+- Output: `false`
+
+### Constraints:
+
+- `1 <= s1.length, s2.length <= 10^4`
+- `s1` and `s2` consist of lowercase English letters.
+
+## Approach
+
+```mermaid
+flowchart TD
+  S(["checkInclusion(s1, s2)"]) --> G{"k = len(s1) > len(s2)?"}
+  G -- yes --> X(["return False"])
+  G -- no --> I["need = Counter(s1), window = Counter()"]
+  I --> L{"more (right, c) in s2?"}
+  L -- no --> E(["return False"])
+  L -- yes --> A["window[c] += 1"]
+  A --> B{"right >= k? — window is now longer than k"}
+  B -- yes --> C["drop s2[right - k] from window, deleting the key at 0"]
+  B -- no --> Q
+  C --> Q{"window == need?"}
+  Q -- yes --> R(["return True"])
+  Q -- no --> L
+```
+
+## Solution
+
+```py
+from collections import Counter
+
+
+class Solution:
+    def checkInclusion(self, s1: str, s2: str) -> bool:
+        k = len(s1)
+        if k > len(s2):
+            return False
+
+        need = Counter(s1)
+        window = Counter()
+
+        for right, c in enumerate(s2):
+            window[c] += 1
+            if right >= k:
+                left_char = s2[right - k]
+                window[left_char] -= 1
+                if window[left_char] == 0:
+                    del window[left_char]
+            if window == need:
+                return True
+
+        return False
+```
+
+## Explanation
+
+<YouTube id="UbyhOgBN834" title="Permutation in String - Leetcode 567 - Python" />